Examine source code of Nature

{
  "name": "Nature",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "FP1220446 (Custom).jpg"
    },
    "colors": {
      "frame": "rgba(18, 150, 42, 1)",
      "tab_background_text": "rgba(242, 237, 237, 1)",
      "toolbar": "rgba(7, 105, 22, 1)",
      "bookmark_text": "rgba(245, 231, 231, 1)",
      "toolbar_field": "rgba(8, 79, 12, 1)",
      "toolbar_field_text": "rgba(232, 247, 15, 1)",
      "tab_line": "rgba(242, 233, 233, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{2d7b6e2c-69c4-4e63-b6b3-198f97cff1eb}"
    }
  }
}